Accumulator recoil cylinder with oil film applicator

ABSTRACT

An oil film applicator for the gas sealing means of a piston in a horizontally disposed accumulator cylinder in a crawler track recoil and adjuster device. The accumulator cylinder is substantially filled with an oil-saturated polyurethane foam which assures complete lubrication of all portions of said sealing means.

United States Patent Alexander [451 Sept. 19, 1972 [54] ACCUMULATOR RECOIL CYLINDER 2,753,892 7/1956 Deardorff ..138I3l WITH OIL FILM APPLICATOR 2,837,380 6/1958 Mazzarins ..305/l0 2,837,379 6/1958 Selyem ..305/l0 m] Imam" Alexander Pekm' 2,837,378 6/1958 Williams ..305/10 [73] Assignee: Caterpillar Tractor Co., Peoria, 111. 0 PUBLICATIONS [22] Filed: Oct-l4 1970 v c d G Prin d A N 1 095 681 D or es, erman te o. ec. 21 Appl. No.1 80,680 22, 1960 pp [52] US. Cl. ..305/l0, 92/153, 138/31, Primary Examiner-Richard Johnson 184/18, 267/64 R, 213/43 Attorney-Fryer, Tjensvold, Feix, Phillips & Lempio [51] Int. Cl. ..B62d 52/30 [58] Field of Search ..92/l53, 155; 188/268, 269; ABSTRACT 213/43; 277/32; 305/10; 138/30, 31, 26; An Oil film a ppllcator for the gas sealing means of a 267/64 60/51 ,184/ 25 piston in a horizontally disposed accumulator cylinder 56] R Cited in a crawler track recoil and adjuster device. The ace creams cumulator cylinder is substantially filled with an oil- UNITED STATES PATENTS saturated polyurethane foam which assures complete lubrication of all portions of said sealing means. 3,425,522 2/ 1969 Gryhlas ..2l3/43 1,028,426 6/1912 Braymer ..184/19 X 12 Claims, 4 Drawing Figures PATENTED SEP 1 9 1972 SHEET 1 BF 2 mm mm INVENTOR GEORGE F. ALEXANDER P'A'TENTEDsEP 19 I972 3,692,368

sum 2 OF 2 INVENTOR GEORGE F. ALEXANDER ATTORN EYS ACCUMULATOR RECOIL CYLINDER WITH OIL FILM APPLICATOR BACKGROUND OF THE INVENTION This invention relates to a new and improved gas accumulator recoil and track adjuster system for crawler vehicles. More particularly, the invention is directed to a novel means for continuously lubricating the piston seals in a horizontally disposed accumulator recoil cylinder.

in rough terrain applications, crawler-type, earthworking vehicles experience sudden impact loading which can cause sever damage to the track components unless means are provided to absorb track recoil and cushion the system. Also, under these conditions, normal wear on the rollers, idler wheel and other components will decrease the tension in the track and adjustment will be required while in the field.

In the past, compression coil springs have been utilized in combination with a movable idler wheel as track recoil means. While the mechanical spring system has been somewhat successful in absorbing recoil, it has proven to be an extremely difficult system to adjust, particularly while in the field. The springs, sometimes preloaded to a force of approximately forty tons, require special tools for adjustment and present a hazard if the energy therein is accidentally released during maintenance.

Another type of recoil means utilizes a piston and a compressed gas cylinder or accumulator in place of the aforementioned mechanical spring and also uses an incompressible fluid system to provide facile adjustment of track tension. Such a system is shown in U.S. Pat. No. 2,837,380 to Mazzarins.

While the gas accumulator recoil system shown by Mazzarins is effective, such designs could fail after a relatively short time due to gas leakage around the sealing means for the piston contained within the gas cylinder. Due to the horizontal disposition of the gas recoil cylinders which are generally used on crawler vehicles, the upper regions of the piston seals in the accumulators become lubricant starved and tend to dry out with consequent ineffectiveness and gas leakage therepast.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevation view of the track of crawler vehicle showing the recoil and adjuster means of the present invention in its operative orientation;

FIG. 2 is a partially sectioned top elevation of the instant recoil and adjuster means taken along the line II- II of FIG. 1;

FIG. 3 is a view similar to that of FIG. 2 but showing I a modified embodiment of the present invention; and

This invention is principally directed to a gas'accurecoil and adjuster system which is readilyinstalled and adjusted in the field.

Still another object of this invention is to provide a combination hydraulic track tension adjuster and recoil means which is sealed from foreign objects and, therefore, not susceptible to jamming.

Yet another object of this invention is to provide a gas accumulator track recoil arrangement which is readily adapted to use in conjunction with standard track adjusting apparatus.

FIG. 4 is a sectional view of another modification of the track recoil and adjuster means of the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENT FIG. 1 shows the track assembly of a typical crawler vehicle. The track 26 is driven by a sprocket wheel 10 which is carried on the rear portion of the roller frame 14 and is supported at the front of the vehicle by an idler wheel 1 1. The gas recoil and track adjuster system of the present invention is shown generally at 13 and comprises a horizontally disposed gas accumulator 28 which is affixed by bracket means 12 to the track roller frame 14. The idler wheel 11 is slidably mounted upon the frame and is attached by means of a piston assemblage 22 to the recoil and adjuster arrangement 13. The idler wheel moves rearwardly whenever it encounters, with sufficient force, rough objects in the terrain.

As is shown in FIG. 2, the preferred embodiment of the recoil and adjuster arrangement of the present invention includes a horizontally disposed gas accumulator cylinder 28 which is bolted at 18 to a track tension adjuster system shown generally at 16. This adjuster system employs a floating piston 20 and a rearwardly opening, high-pressure grease cylinder 23 which is supported in a tubular guide shroud 24. A fitting 38 in the rear accumulator wall is provided for charging the accumulator cylinder with nitrogen gas, in the conventional manner, to a pressure of approximately 1,300 psi. A vent is provided at 37 to prevent the creation of pressure conditions which might inhibit the movement of the pistons 29 and 20.

The recoil system gas cylinder 28 receives a freefloating piston 29 between the limits of one fixed end wall 30 and one detachable end wall 32. The piston has bearing means 31 which coact with the cylinder wall to provide for accurate centering and sealing means, in the form of piston rings 40, are also provided. The accumulator wall 30 is provided with an aperture 33 through which the extension 34 to piston 20 is received. The extension 34 operatively abuts the piston 29. v

In accordance with the present invention, the accumulator cylinder is filled during assembly with a flexi ble polyurethane foam 42 which is presaturated with lubricating oil. The particular polyurethane foam used in the preferred embodiment is polyester-based, lowdensity and flexible. However, one skilled in the art will readily recognize that other foams with comparable characteristics could be utilized without departing from the principles of this invention. Foams of low density, i.e., approximately two pounds per cubic foot, which are relatively unaffected by the lubricating oil used, and which have an uncompressed voidness in the vicinity of 97 percent so as not to significantly diminish the gas cylinder volume,'can be utilized. In addition to the foam named, low-density Polyethylene foam, and Styreneacrylonitrile foam might also be used.

When in use, the cylinder 28 is charged with nitrogen gas which fills the voids in the oil-saturated foam 42 FIG. 2. Capillary action, resulting from the cyclic compression of the foam by the recoil piston 29 disperses the lubricating oil uniformly throughout the entire body of foam and the inner surface of the cylinder 28. An oil film is deposited on the interior walls of the cylinder which continuously provides adequate lubrication for the upper portions of the piston seals 40 in the horizontally disposed recoil system.

A fitting 39 is provided for the passage of high-pressure grease 41 to thecylinder 23. The incompressible grease 41 forms a variable-volume fluid piston which actuates the pistons and 29 to provide tensioning for the idler wheel 11 and, in turn, the track 26. It will be readily appreciated that admission of grease to the chamber will increase track tension whereas withdrawal of grease will decrease said tension. These operations can be readily carried out in the field without requiring modification of the gas pressure in the accumulator cylinder 28.

When the crawler vehicle encounteres a rough object in its path, the idler wheel and consequently the adjuster assemblage 22 and floating piston 20 are thrust against the recoil piston 29 with consequent compression of ,the gas and the foam in the accumulator cylinder 28. With each such movement, lubricating oil is uniformly dispersed throughout the interior of the accumulator cylinder in the previously-described manner.

FIGS. 3 and 4 show alternate embodiments of the recoil and track adjuster system which are well suited for. inclusion of the novel principles of the present invention. The embodiment of FIG. 3 differs from that shown in FIG. 2 in the manner of application of force to the recoil piston '29. As shown, the adjuster piston 20 does not directly abut the recoil piston but rather abuts a body of incompressible fluid 41 such as grease which, in turn, abuts the recoil piston. One of the salient features of this arrangement is that, by using the liquid piston formed by the body of grease 41, a distance differential is created between the adjuster piston and the recoil piston. The volume of the foam 42' contained in accumulator cylinder being greater than that of the grease contained in the cylinder 23', an incremental leftward movement of the adjuster piston will produce a lesser leftward movement of the recoil piston. This has the obvious advantage of allowing a shorter recoil piston stroke for any given recoil force required, with consequent savings in accumulator cylinder size.

The embodiment shown in FIG. 4 utilizes the oil-impregnated polyurethane foam 42" in a conventional, directly-connected recoil and track adjuster system. In this embodiment, the gas cylinder and the grease cylinder 41." are combined into one housing 23" wherein the respective fluids are separated by the piston 29". The piston rod 20 forms a direct connection between the idler wheel and the recoil piston.

It should be noted that although the novel recoil and adjuster system of the present invention has. been described herein in relation to a crawler vehicle, it is" apparent that said system has utility in any other type of arrangement wherein recoil and tension adjustment means are required.

While the preferred embodiments of the invention have been illustrated and described, it is to be understood that these embodiments are capable of variation and modification and are not limited to the precise details set forth, but rather include such variations and modifications as fall within the scope of the appended claims.

I claim:

1. In a hydraulic recoil device for the track of a crawler vehicle; a gas accumulator cylinder operatively containing piston means, seal means between said cylinder and said piston means, recoil transmitting means operatively connecting said piston means to said track and resilient structural means within said accumulator cylinder for dispersing lubricant to all portions of said seal means.

2. The hydraulic recoil device of claim 1 wherein said recoil transmitting means includes means to adjust the tension in said track.

3. The hydraulic recoil device of claim 1 wherein the axis of said accumulator cylinder is disposed horizontally.

4. The hydraulic recoil device of claim 1 wherein said resilient structural means include open-cell plastic foam means for dispersing lubricant-therethrough.

5..The hydraulic recoil device of claim 4 wherein the plastic foam means is low-density polyurethane.

6. The hydraulic recoil device of claim 4 wherein said plastic foam means has an uncompressed voidness of at least 97 percent.

7. The hydraulic recoil device of claim 2 wherein said adjuster means includes a high-pressure grease cylinder operatively disposed between said accumulator cylinder and said track and wherein the addition of grease to said grease cylinder increases the tension in said track and withdrawal of grease from said grease cylinder decreases the tension in said track.

8. The hydraulic recoil device of claim 7 wherein said piston means is free-floating within said accumulator cylinder and wherein said grease in said grease cylinder forms a fluid piston which acts directly upon said free-floating piston means.

9. The hydraulic recoil device of claim 6 wherein said accumulator cylinder and said grease cylinder have a unitary housing containing said piston means and wherein said piston means includes a piston rod means which is directly associated with said track.

' grease cylinder having a piston with a piston rod wherein said piston rod abuts said piston means in said accumulator cylinder and' resilient structural means within said accumulator cylinder for dispersing lubricant to all portions of said seal means.

11. In a hydraulic recoil device for absorbing recoil between two relatively movable members; a gas accumulator cylinder operatively containing piston means, seal means between said cylinder and said piston means, recoil transmitting means for operatively connecting said piston means to one of said relatively movable members, said recoil transmitting means including means for adjusting the spacing between said two members, and resilient structural means disposed within said gas accumulator cylinder for dispersing lubricant to all portions of said seal means.

12. The hydraulic recoil device of claim 11 wherein said resilient structural means include open-cell plastic foam means for dispersing lubricant therethrough by means of capillary action. 

1. In a hydraulic rEcoil device for the track of a crawler vehicle; a gas accumulator cylinder operatively containing piston means, seal means between said cylinder and said piston means, recoil transmitting means operatively connecting said piston means to said track and resilient structural means within said accumulator cylinder for dispersing lubricant to all portions of said seal means.
 2. The hydraulic recoil device of claim 1 wherein said recoil transmitting means includes means to adjust the tension in said track.
 3. The hydraulic recoil device of claim 1 wherein the axis of said accumulator cylinder is disposed horizontally.
 4. The hydraulic recoil device of claim 1 wherein said resilient structural means include open-cell plastic foam means for dispersing lubricant therethrough.
 5. The hydraulic recoil device of claim 4 wherein the plastic foam means is low-density polyurethane.
 6. The hydraulic recoil device of claim 4 wherein said plastic foam means has an uncompressed voidness of at least 97 percent.
 7. The hydraulic recoil device of claim 2 wherein said adjuster means includes a high-pressure grease cylinder operatively disposed between said accumulator cylinder and said track and wherein the addition of grease to said grease cylinder increases the tension in said track and withdrawal of grease from said grease cylinder decreases the tension in said track.
 8. The hydraulic recoil device of claim 7 wherein said piston means is free-floating within said accumulator cylinder and wherein said grease in said grease cylinder forms a fluid piston which acts directly upon said free-floating piston means.
 9. The hydraulic recoil device of claim 6 wherein said accumulator cylinder and said grease cylinder have a unitary housing containing said piston means and wherein said piston means includes a piston rod means which is directly associated with said track.
 10. In a hydraulic recoil device for the track of a crawler vehicle; a gas accumulator cylinder operatively containing piston means, seal means between said cylinder and said piston means, recoil transmitting means operatively connecting said piston means to said track, said recoil transmitting means including means to adjust the tension in said track, said tension adjusting means including a high-pressure grease cylinder operatively disposed between said accumulator cylinder and said track wherein the addition of grease to said grease cylinder increases track tension and withdrawal of grease from said grease cylinder decreases tension, said grease cylinder having a piston with a piston rod wherein said piston rod abuts said piston means in said accumulator cylinder and resilient structural means within said accumulator cylinder for dispersing lubricant to all portions of said seal means.
 11. In a hydraulic recoil device for absorbing recoil between two relatively movable members; a gas accumulator cylinder operatively containing piston means, seal means between said cylinder and said piston means, recoil transmitting means for operatively connecting said piston means to one of said relatively movable members, said recoil transmitting means including means for adjusting the spacing between said two members, and resilient structural means disposed within said gas accumulator cylinder for dispersing lubricant to all portions of said seal means.
 12. The hydraulic recoil device of claim 11 wherein said resilient structural means include open-cell plastic foam means for dispersing lubricant therethrough by means of capillary action. 